Cigarette smoking among adolescents and young adults remains one of the most important public health challenges. Almost all smokers begin smoking while in their adolescent years, but smoking becomes entrenched during the young adult years. Understanding more about the factors that promote or protect against smoking progression and nicotine dependence may help us to develop more effective interventions. Also important is understanding how the transition from adolescence to young adulthood, a transition that brings multiple life changes and heightened risk for behavioral problems, influences smoking patterns that have been set in motion during adolescence. This program project will provide an in-depth, multi-method study of the patterns and predictors of smoking patterns from experimentation onward, from adolescence through young adulthood. This continuation builds on and extends our current work by proposing to continue to follow a high risk cohort of individuals, first identified and characterized during mid-adolescence, and who are now in young adulthood. We propose to follow these individuals through their early twenties, the period of highest risk for establishment of smoking and dependence. We will maintain our focus on the social emotional contexts that may influence smoking, and extend this to explore promising genetic markers for the development of dependence. Across projects, we will also characterize, through multiple methods, the development of dependence from the early stages of smoking onward. The projects are linked conceptually through their common consideration of factors that influence the patterns of smoking from adolescence through young adulthood, and methodologically, through their use of a common cohort of participants. Our overriding interest is in identifying, describing, and predicting patterns of progression of smoking and nicotine dependence, considering the dynamic interplay of genetic, social, and emotional contexts. Our proposed program project comprises four research projects and three cores. The four research projects are: 1) Patterns and Predictors of Smoking from Adolescence to Young Adulthood; 2) Proximal Contexts of Young Adult Smoking Patterns; 3) Emotional Indices of Withdrawal in Young Adult Smokers;and 4) Genetic Risk Markers for Smoking Progression. Our three Cores are: 1) Scientific/Administrative Core; 2) Participant Interaction Core;and 3) Data Management, Measurement, and Statistics Core.